RESUMEN

Corneal dystrophies are a group of rare genetic eye disorders characterized by the accumulation of abnormal material in different layers of the cornea, potentially leading to vision impairment. In vivo confocal microscopy (IVCM) is an emerging non-invasive imaging and diagnostic tool that helps study the ocular surface microstructure. This case report examines the clinical characteristics of Avellino corneal dystrophy in a young patient through the use of slit lamp examination, IVCM, and optical coherence tomography (OCT) in order to assess the effectiveness of these non-invasive tests as diagnostic tools.

RESUMEN

Granular corneal dystrophy type 2 (GCD2) is an autosomal dominant corneal stromal dystrophy that is caused by p.Arg124His mutation of transforming growth factor ß induced (TGFBI) gene. It is characterized by well demarcated granular shaped opacities in central anterior stroma and as the disease progresses, extrusion of the deposits results in ocular pain due to corneal epithelial erosion. Also, diffuse corneal haze which appears late, causes decrease in visual acuity. The prevalence of GCD2 is high in East Asia including Korea. Homozygous patients show a severe phenotype from an early age, and the heterozygote phenotype varies among patients, depending on several types of compound heterozygous TGFBI mutations. In the initial stage, conservative treatments such as artificial tears, antibiotic eye drops, and bandage contact lenses are used to treat corneal erosion. Different surgical methods are used depending on the depth and extent of the stromal deposits. Phototherapeutic keratectomy removes anterior opacities and is advantageous in terms of its applicability and repeatability. For deeper lesions, deep anterior lamellar keratoplasty can be used as the endothelial layer is not always affected. Recurrence following these treatments are reported within a wide range of rates in different studies due to varying definition of recurrence and follow-up period. In patients who have undergone corneal laser vision-correction surgeries such as photorefractive keratectomy, LASEK, or LASIK including SMILE surgery, corneal opacity exacerbates rapidly with severe deterioration of visual acuity. Further investigations on new treatments of GCD2 are necessary.

Asunto(s)

Distrofias Hereditarias de la Córnea , Opacidad de la Córnea , Úlcera de la Córnea , Queratomileusis por Láser In Situ , Queratectomía Fotorrefractiva , Humanos , Distrofias Hereditarias de la Córnea/diagnóstico , Distrofias Hereditarias de la Córnea/genética , Distrofias Hereditarias de la Córnea/terapia , Córnea/patología , Queratectomía Fotorrefractiva/métodos , Queratomileusis por Láser In Situ/efectos adversos , Opacidad de la Córnea/diagnóstico , Opacidad de la Córnea/etiología , Opacidad de la Córnea/terapia , Úlcera de la Córnea/cirugía , Factor de Crecimiento Transformador beta/genética

RESUMEN

The progressive degeneration of granular corneal dystrophy type 2 (GCD2) corneal fibroblasts is associated with altered mitochondrial function, but the underlying mechanisms are incompletely understood. We investigated whether an imbalance of mitochondrial dynamics contributes to mitochondrial dysfunction of GCD2 corneal fibroblasts. Transmission electron microscopy revealed several small, structurally abnormal mitochondria with altered cristae morphology in GCD2 corneal fibroblasts. Confocal microscopy showed enhanced mitochondrial fission and fragmented mitochondrial tubular networks. Western blotting revealed higher levels of MFN1, MFN2, and pDRP1 and decreased levels of OPA1 and FIS1 in GCD2. OPA1 reduction by short hairpin RNA (shRNA) resulted in fragmented mitochondrial tubular networks and increased susceptibility to mitochondrial stress-induced apoptosis. A decrease in the mitochondrial biogenesis-related transcription factors NRF1 and PGC1α was observed, while there was an increase in the mitochondrial membrane proteins TOM20 and TIM23. Additionally, reduced levels of mitochondrial DNA (mtDNA) were exhibited in GCD2 corneal fibroblasts. These observations suggest that altered mitochondrial fission/fusion and biogenesis are the critical molecular mechanisms that cause mitochondrial dysfunction contributing to the degeneration of GCD2 corneal fibroblasts.

Asunto(s)

Distrofias Hereditarias de la Córnea , GTP Fosfohidrolasas , Humanos , Apoptosis/genética , Distrofias Hereditarias de la Córnea/genética , Fibroblastos/metabolismo , GTP Fosfohidrolasas/genética , GTP Fosfohidrolasas/metabolismo , Mitocondrias/genética , Mitocondrias/metabolismo

RESUMEN

PURPOSE: To evaluate the corneal biomechanical features of eyes with granular corneal dystrophy type 2 (GCD2) by analyzing corneal biomechanical indices obtained using a Corvis ST (CST) dynamic ultra-high-speed Scheimpflug imaging device. METHODS: In this retrospective case-control study, 35 CST parameters were compared in normal eyes (control) and eyes of patients with GCD2 treated at Osaka University Hospital, Osaka, Japan. The parameters included the Corvis Biomechanical Index (CBI), which is important in differentiating eyes with keratoconus from normal eyes. We measured the deposition rates of lesions in the central 7-mm region of the eye and assessed the correlation between the deposition rate and the CBI. RESULTS: Twenty-one eyes with GCD2 and 23 control eyes were analyzed. Eyes with GCD2 showed significantly less corneal stiffness in 15 CST parameters than did control eyes. In particular, the CBI was remarkably higher in eyes with GCD2 than in control eyes (P = 0.000006). Additionally, the deposition rate and the CBI were positively correlated. CONCLUSIONS: GCD2 eyes had softer corneas than did control eyes in most biomechanical CST parameters, and one of the parameters (the CBI) was linked to the rate of deposited lesions. Since IOP may be underestimated in GCD2 eyes, management should be especially careful in GCD2 cases complicated by glaucoma.

Asunto(s)

Córnea , Queratocono , Humanos , Estudios Retrospectivos , Estudios de Casos y Controles , Elasticidad , Queratocono/diagnóstico , Fenómenos Biomecánicos , Topografía de la Córnea/métodos

RESUMEN

AIM: To reveal the importance of TGFBI gene screening for candidates with a family history of corneal disease or granular opacities in corneal stroma before refractive surgery. METHODS: A 37-year-old male (proband) underwent bilateral laser-assisted in situ keratomileusis (LASIK) in 2002, with right vision decreased significantly in 2006. The proband and other 32 members of the family underwent a detailed ophthalmic examination, including vision acuity, intraocular pressure, slit-lamp photograph, fundus examination, optical coherence tomography (OCT) of cornea, and in vivo confocal microscope (IVCM) and peripheral blood was used for genomic DNA extraction. Seventeen TGFBI gene exons were analyzed via polymerase chain reaction amplification and direct sequencing. RESULTS: Slit-lamp, IVCM, and OCT images showed that a large amount of dense and confluent granular opaque were seen at the interfaces of the flap and remnant stromal bed in right and light degree in left eye. Sanger sequencing showed that there was a 371G>A mutation (CGC>CAC) in exon 4, which indicated that he harbored a heterozygote R124H mutation, identifying the diagnosis of Avellino corneal dystrophy (ACD). Among the other 32 family members, 6 of them harbored the identical mutation to that in the proband. CONCLUSION: ACD will worsen and recur after LASIK. Preoperative gene-screening for TGFBI mutations is important in diagnosing ACD.

RESUMEN

AIM: To evaluate the feasibility of promoting genetic detection for granular corneal dystrophy type 2 (GCD2) by a questionnaire conducted among citizens in five cities in China. METHODS: The data were collected by questionnaire, and analyzed by Chi-square test and one-tailed t test in IBM SPSS statistics. RESULTS: Based on the survey data on the awareness of GCD2 genetic detection in this study and the positive predictive analysis report of the citizens in five cities in China, the vast majority (84.2%) of respondents had never heard of it and did not know that GCD2 patients have been prohibited from performing excimer surgery that can deteriorate GCD2 patients' condition even leading to blindness. Though 3.4% of patients understood GCD2 very much, they have no idea that GCD2 could not be 100% accuracy diagnosed by the conventional inspection methods. CONCLUSION: It is feasible and necessary to use GCD2 genetic detection as an excimer preoperative examination project. In order to promote the development of detection project, a few improvements should be carried out in terms of the promoting efforts, costs, and research progress.

RESUMEN

Granular corneal dystrophy type 2 (GCD2) is the most common form of transforming growth factor ß-induced (TGFBI) gene-linked corneal dystrophy and is pathologically characterized by the corneal deposition of mutant-TGFBIp. The defective autophagic degradation of pathogenic mutant-TGFBIp has been shown in GCD2; however, its exact mechanisms are unknown. To address this, we investigated lysosomal functions using corneal fibroblasts. Levels of cathepsins K and L (CTSK and CTSL) were significantly decreased in GCD2 cells, but of cathepsins B and D (CTSB and CTSD) did not change. The maturation of the pro-enzymes to their active forms (CTSB, CTSK and CTSL) was inhibited in GCD2 cells. CTSL enzymes directly degraded both LC3 (autophagosomes marker) and mutant-TGFBIp. Exogenous CTSL expression dramatically reduced mutant-TGFBIp in GCD2 cells, but not TGFBIp in WT cells. An increased lysosomal pH and clustered lysosomal perinuclear position were found in GCD2 cells. Transcription factor EB (TFEB) levels were significantly reduced in GCD2 cells, compared to WT. Notably, exogenous TFEB expression improved mutant-TGFBIp clearance and lysosomal abnormalities in GCD2 cells. Taken together, lysosomal dysfunction in the corneal fibroblasts underlies the pathogenesis of GCD2, and TFEB has a therapeutic potential in the treatment of GCD2.

Asunto(s)

Factores de Transcripción Básicos con Cremalleras de Leucinas y Motivos Hélice-Asa-Hélice/metabolismo , Córnea/patología , Distrofias Hereditarias de la Córnea/patología , Fibroblastos/metabolismo , Fibroblastos/patología , Lisosomas/metabolismo , Apoptosis , Catepsinas/metabolismo , Núcleo Celular/metabolismo , Proteínas de la Matriz Extracelular/metabolismo , Humanos , Proteínas Mutantes/metabolismo , Factor de Crecimiento Transformador beta/metabolismo

RESUMEN

PURPOSE: Mutations in the transforming growth factor ß-induced protein (TGFBIp) are associated with TGFBI-linked corneal dystrophies, which manifests as protein deposits in the cornea. A total of 70 different disease-causing mutations have been reported so far including the common R124H substitution, which is associated with granular corneal dystrophy type 2 (GCD2). The disease mechanism of GCD2 is not known and the current treatments only offer temporary relief due to the reoccurrence of deposits. EXPERIMENTAL DESIGN: The corneal protein profiles of the three genotypes (wild-type (WT), heterozygotes, and homozygotes) of a GCD2 mouse model are compared using label-free quantitative LC-MS/MS. RESULTS: The mice do not display corneal protein deposits and the global protein expression between the three genotypes is highly similar. However, the expression of mutated TGFBIp is 41% of that of the WT protein. CONCLUSIONS AND CLINICAL RELEVANCE: It is proposed that the lowered expression level of mutant TGFBIp protein relative to WT protein is the direct cause of the missing development of corneal deposits in the mouse. The overall protein profiles of the corneas are not impacted by the reduced amount of TGFBIp. Altogether, this supports a partial reduction in mutated TGFBIp as a potential treatment strategy for GCD2.

Asunto(s)

Córnea/metabolismo , Distrofias Hereditarias de la Córnea/metabolismo , Distrofias Hereditarias de la Córnea/patología , Proteoma/metabolismo , Factor de Crecimiento Transformador beta1/metabolismo , Animales , Córnea/patología , Distrofias Hereditarias de la Córnea/genética , Modelos Animales de Enfermedad , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Ratones , Ratones Transgénicos , Mutación , Fenotipo , Proteoma/análisis , Factor de Crecimiento Transformador beta1/genética

RESUMEN

Alzheimer's disease (AD) primarily affects the brain and is the most common form of dementia worldwide. Despite more than a century of research, there are still no early biomarkers for AD. It has been reported that AD affects the eye, which is more accessible for imaging than the brain; however, links with the cornea have not been evaluated. To investigate whether the cornea could be used to identify possible diagnostic indicators of AD, we analyzed the proteolytic processing and isoforms of amyloid precursor protein (APP) and evaluated the expression of AD-related genes and proteins in corneal fibroblasts from wild-type (WT) corneas and corneas from patients with granular corneal dystrophy type 2 (GCD2), which is related to amyloid formation in the cornea. Reverse transcription polymerase chain reaction (RT-PCR) analysis was used to assess the expression of AD-related genes, i.e., APP, ADAM10, BACE1, BACE2, PSEN1, NCSTN, IDE, and NEP. RT-PCR and DNA sequencing analysis demonstrated that isoforms of APP770 and APP751, but not APP695, were expressed in corneal fibroblasts. Moreover, the mRNA ratio of APP770/APP751 isoforms was approximately 4:1. Western blot analysis also demonstrated the expression of a disintegrin and metalloprotease domain-containing protein 10 (ADAM10), beta-site APP-cleaving enzyme 1 (BACE1), nicastrin, insulin degradation enzyme, and neprilysin in corneal fibroblasts. Among these targets, the levels of immature ADAM10 and BACE1 protein were significantly increased in GCD2 cells. The expression levels of APP, ADAM10, BACE1, and transforming growth factor-beta-induced protein (TGFBIp) were also detected by western blot in human corneal epithelium. We also investigated the effects of inhibition of the autophagy-lysosomal and ubiquitin-proteasomal proteolytic systems (UPS) on APP processing and metabolism. These pathway inhibitors accumulated APP, α-carboxy-terminal fragments (CTFs), ß-CTFs, and the C-terminal APP intracellular domain (AICD) in corneal fibroblasts. Analysis of microRNAs (miRNAs) revealed that miR-9 and miR-181a negatively coregulated BACE1 and TGFBIp, which was directly associated with the pathogenesis of AD and GCD2, respectively. Immunohistochemical analysis indicated that APP and BACE1 were distributed in corneal stroma cells, epithelial cells, and the retinal layer in mice. Collectively, we propose that the cornea, which is the transparent outermost layer of the eye and thus offers easy accessibility, could be used as a potential biomarker for AD diagnosis and progression.

Asunto(s)

Enfermedad de Alzheimer/complicaciones , Precursor de Proteína beta-Amiloide/genética , Distrofias Hereditarias de la Córnea/genética , Epitelio Corneal/metabolismo , Regulación de la Expresión Génica , ARN/genética , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Precursor de Proteína beta-Amiloide/biosíntesis , Animales , Biomarcadores/metabolismo , Western Blotting , Células Cultivadas , Distrofias Hereditarias de la Córnea/metabolismo , Distrofias Hereditarias de la Córnea/patología , Ensayo de Inmunoadsorción Enzimática , Epitelio Corneal/patología , Fibroblastos/metabolismo , Fibroblastos/patología , Humanos , Inmunohistoquímica , Ratones

RESUMEN

Melatonin (MT), an effective antioxidant, has therapeutic implications for granular corneal dystrophy type 2 (GCD2) treatment. Eye drop formulations containing cyclodextrins (CDs) were studied with the objective of improving MT solubility, stability, and ocular absorption, while decreasing eye irritation. MT complexes with αCD, ßCD, γCD, and 2-hydroxypropyl-ßCD (HPßCD) were characterized by phase solubility studies, which demonstrated Higuchi's AL-type phase solubility profiles. The MT/HPßCD complex showed the highest MT solubility (2.75mg/mL). Ocular irritation experiments showed HPßCD inclusion alleviated irritation of the eye. After administration of MT formulations to rabbit corneas, each harvested cornea was separated into corneal epithelium, stroma, and endothelium. MT concentrations in the corneal epithelium, stroma, and endothelium for the F1-treated group were 55.5±9.24, 26.7±2.66, and 21.1±1.77µM while those for the F2-treated group were 127.2±21.01, 43.7±16.93, and 51.0±13.91µM, respectively. Stability studies for 60days showed no significant change in pH, osmolarity, and MT content. In conclusion, MT/HPßCD formulations can lower irritation, enhance MT stability, and improve therapeutic efficacy.

Asunto(s)

2-Hidroxipropil-beta-Ciclodextrina/química , Distrofias Hereditarias de la Córnea/tratamiento farmacológico , Sistemas de Liberación de Medicamentos , Melatonina/farmacología , Soluciones Oftálmicas/farmacología , Animales , Córnea , Conejos , Solubilidad , beta-Ciclodextrinas

RESUMEN

PURPOSE: The purpose of this study was to evaluate visual function and postoperative refractive errors in patients with granular corneal dystrophy type 2 (GCD2) and cataracts who underwent photorefractive keratectomy (PRK) instead of phototherapeutic keratectomy (PTK) following cataract surgery to avoid PTK-induced central island formation and reduce refractive errors after cataract surgery. METHODS: The medical records of 14 eyes from nine patients (one man and eight women; mean age, 69.0 ± 8.5 years) with GCD2 and cataracts were evaluated. All patients underwent PTK using the PRK mode 3 months after cataract surgery. We analyzed corrected distance visual acuity (CDVA), refractive errors, and corneal astigmatism derived from Fourier analysis and assessed the incidence of complications in cataract surgery and PTK. RESULTS: The mean CDVA logMAR values were 0.42 ± 0.19, 0.38 ± 0.18, and 0.16 ± 0.12 before and after cataract surgery and after PTK, respectively. CDVA improved significantly after PTK, as compared with both before and after cataract surgery (P < 0.001). The mean absolute errors after cataract surgery and PTK were 0.53 ± 0.43 and 1.61 ± 1.01 diopters, respectively. Pre- and postoperative Fourier indices did not significantly vary in the 3-mm diameter zone, and only the asymmetry component of the 6-mm diameter zone significantly (P <0.01) increased postoperatively. No central island formation and no other marked complications were observed postoperatively in any case. CONCLUSIONS: Performing PTK using the PRK mode following cataract surgery may be effective for patients with GCD2 and cataracts.

Asunto(s)

Distrofias Hereditarias de la Córnea/cirugía , Miopía/cirugía , Queratectomía Fotorrefractiva , Anciano , Anciano de 80 o más Años , Catarata/fisiopatología , Distrofias Hereditarias de la Córnea/fisiopatología , Topografía de la Córnea , Femenino , Análisis de Fourier , Humanos , Implantación de Lentes Intraoculares , Masculino , Persona de Mediana Edad , Miopía/fisiopatología , Facoemulsificación , Refracción Ocular/fisiología , Tomografía de Coherencia Óptica , Resultado del Tratamiento , Agudeza Visual/fisiología

RESUMEN

PURPOSE: To compare the accuracy of several methods of intraocular lens (IOL) power calculations used for cataract surgery in eyes treated with phototherapeutic keratectomy (PTK) that results in changes in the anterior corneal surface and axial length; these results make power calculations less predictable. METHODS: We evaluated the medical records of 23 eyes of 13 patients (mean age, 68.8 years; range 62-80 years) who underwent cataract surgery after PTK at Keio University Hospital, Tokyo, Japan. The prediction error, defined as the difference between the estimated postoperative spherical equivalent and the postoperative manifest refraction at the spectacle plane, was calculated using five formulas: SRK/T, Haigis-L, Shammas-PL, Camellin-Calossi, and OKULIX ray tracing software. We compared the median values of the arithmetic and absolute prediction errors among the five formulas. RESULTS: The median arithmetic errors after cataract surgery for the five formulas were 0.70 D (diopter) (range -0.41 to 2.78), -0.96 D (range -2.14 to 0.81), -0.81 D (range -1.89 to 1.15), -0.04 D (range -1.35 to 1.47), and 0.68 D (range -0.61 to 2.50), respectively. CONCLUSION: The Camellin-Calossi formula is a good option for calculating IOL powers in eyes that underwent PTK.

Asunto(s)

Extracción de Catarata , Catarata/complicaciones , Distrofias Hereditarias de la Córnea/complicaciones , Lentes Intraoculares , Queratectomía Fotorrefractiva , Refracción Ocular , Anciano , Anciano de 80 o más Años , Distrofias Hereditarias de la Córnea/cirugía , Humanos , Persona de Mediana Edad , Reproducibilidad de los Resultados , Estudios Retrospectivos

RESUMEN

Transforming growth factor-ß (TGF-ß)-induced gene (TGFBI) protein (TGFBIp) is associated with granular corneal dystrophy type 2 (GCD2). TGFBIp levels can affect GCD2 phenotypes, but the underlying molecular mechanisms have not been fully elucidated. We investigated the involvement of microRNA (miRNA) and TGF-ß in the regulation of TGFBIp expression in corneal fibroblasts. Ectopic expression of miR-9, miR-21, and miR-181a significantly decreased TGFBIp levels. Conversely, expression of miR-21 and miR-181a was induced by TGF-ß1. Expression of miR-21 was 10-fold higher than that of miR-9 and miR-181a in corneal fibroblasts. Additionally, TGF-ß1 expression was significantly higher than that of TGF-ß2 and TGF-ß3 in corneal fibroblasts, whereas expression of all three TGF-ß forms was not significantly different between wild-type (WT) and GCD2 homozygotes (HO) corneal fibroblasts. Taken together, these data indicate that TGFBIp expression is positively regulated by TGF-ß, whereas TGF-ß-induced miR-21 and miR-181a negatively regulate TGFBIp expression. In conclusion, TGFBIp levels in corneal fibroblasts are controlled via the coordinated activity of miR-21 and miR-181a and by Smad signaling. Pharmacologic modulation of these miRNAs and TGF-ß signaling could have therapeutic potential for TGFBI-associated corneal dystrophy, including GCD2.

Asunto(s)

Córnea/metabolismo , Proteínas de la Matriz Extracelular/genética , Proteínas de la Matriz Extracelular/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Proteínas Smad/metabolismo , Factor de Crecimiento Transformador beta1/metabolismo , Factor de Crecimiento Transformador beta/genética , Factor de Crecimiento Transformador beta/metabolismo , Células Cultivadas , Córnea/citología , Distrofias Hereditarias de la Córnea/genética , Distrofias Hereditarias de la Córnea/metabolismo , Distrofias Hereditarias de la Córnea/patología , Fibroblastos/citología , Fibroblastos/metabolismo , Regulación de la Expresión Génica , Homocigoto , Humanos , Modelos Biológicos , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Mutación Puntual , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transducción de Señal

RESUMEN

More than 60 mutations in transforming growth factor beta-induced protein (TGFBIp) have been reported in humans causing a variety of phenotypic protein aggregates in the cornea, commonly termed corneal dystrophies. One mutation, generating an arginine to histidine amino acid substitution at position 124 in mature TGFBIp leads to granular corneal dystrophy type 2 (GCD2). Homozygous GCD2 cases develop massive protein accumulation early in life whereas heterozygous GCD2 cases become affected much later and generally with a much less severe outcome. However, if heterozygous GCD2 patients undergo laser-assisted in situ keratomileusis (LASIK) surgery protein accumulation is accelerated and they develop massive protein accumulations a few years after surgery. Here, we present the protein profile of aggregate-containing corneal tissue from GCD2 patients with a history of LASIK surgery using LC-MS/MS. Label-free quantification of corneal extracellular matrix proteins showed accumulation of TGFBIp. This was supported by 2DE and immunoblotting against TGFBIp that revealed the accumulation of full-length TGFBIp. In addition, a high molecular weight TGFBIp complex was more apparent in GCD2 patients after LASIK surgery, which may be important for the disease progression. Lastly, 2DE also revealed differential processing between GCD2 patients with a history of LASIK surgery when compared to healthy individuals.

Asunto(s)

Distrofias Hereditarias de la Córnea/cirugía , Proteínas de la Matriz Extracelular/metabolismo , Queratomileusis por Láser In Situ/efectos adversos , Agregación Patológica de Proteínas/metabolismo , Proteolisis , Proteoma/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Adulto , Estudios de Casos y Controles , Cromatografía Liquida , Córnea/metabolismo , Córnea/patología , Córnea/cirugía , Distrofias Hereditarias de la Córnea/genética , Distrofias Hereditarias de la Córnea/metabolismo , Distrofias Hereditarias de la Córnea/patología , Proteínas de la Matriz Extracelular/genética , Femenino , Expresión Génica , Homocigoto , Humanos , Masculino , Anotación de Secuencia Molecular , Peso Molecular , Mutación , Agregación Patológica de Proteínas/etiología , Agregación Patológica de Proteínas/genética , Agregación Patológica de Proteínas/patología , Multimerización de Proteína , Proteoma/genética , Espectrometría de Masas en Tándem , Factor de Crecimiento Transformador beta/genética

RESUMEN

Transforming growth factor beta-induced (TGFBI) corneal dystrophies are a group of inherited progressive corneal diseases. Accumulation of transforming growth factor beta-induced protein (TGFBIp) is involved in the pathogenesis of TGFBI corneal dystrophies; however, the exact molecular mechanisms are not fully elucidated. In this review article, we summarize the current knowledge of TGFBI corneal dystrophies including clinical manifestations, epidemiology, most common and recently reported associated mutations for each disease, and treatment modalities. We review our current understanding of the molecular mechanisms of granular corneal dystrophy type 2 (GCD2) and studies of other TGFBI corneal dystrophies. In GCD2 corneal fibroblasts, alterations of morphological characteristics of corneal fibroblasts, increased susceptibility to intracellular oxidative stress, dysfunctional and fragmented mitochondria, defective autophagy, and alterations of cell cycle were observed. Other studies of mutated TGFBIp show changes in conformational structure, stability and proteolytic properties in lattice and granular corneal dystrophies. Future research should be directed toward elucidation of the biochemical mechanism of deposit formation, the relationship between the mutated TGFBIp and the other materials in the extracellular matrix, and the development of gene therapy and pharmaceutical agents.

Asunto(s)

Distrofias Hereditarias de la Córnea , Factor de Crecimiento Transformador beta/metabolismo , Autofagia/fisiología , Córnea/metabolismo , Distrofias Hereditarias de la Córnea/etiología , Distrofias Hereditarias de la Córnea/genética , Distrofias Hereditarias de la Córnea/metabolismo , Distrofias Hereditarias de la Córnea/terapia , Fibroblastos/patología , Predisposición Genética a la Enfermedad , Humanos , Mutación , Estrés Oxidativo/fisiología

RESUMEN

The International Committee for Classification of Corneal Dystrophies (IC3D) provides updated data to ophthalmologists by incorporating traditional definitions of corneal dystrophies with new genetic, clinical, and pathologic information. Recent advances in the genetics of corneal dystrophies facilitate more precise classifications and elucidate each classification's molecular mechanisms. Unfortunately, the molecular mechanisms and underlying pathogenic mechanisms have remained obscure, with the exception of Schnyder corneal dystrophy (CD), granular CD type 2 (GCD2), and Fuch's endothelial CD. Here, we review the pathogenesis of Schnyder CD and GCD2.

Asunto(s)

Distrofias Hereditarias de la Córnea/genética , Humanos , Metabolismo de los Lípidos , Mitocondrias/metabolismo , Modelos Biológicos , Estrés Oxidativo

RESUMEN

BACKGROUND: Mutations in the transforming growth factor ß-induced gene (TGFBI) are major causes of genetic corneal dystrophies (CDs), which can be grouped into TGFBI CDs. Although a few studies have reported the clinical and genetic features of Korean patients with TGFBI CD, no data are available regarding the frequency and spectrum of TGFBI mutations in a consecutive series of Korean patients with clinically diagnosed CDs. METHODS: Patients with any type of CD, who underwent both ophthalmologic examination and TGFBI gene analysis by Sanger sequencing at a tertiary care hospital in Seoul, Korea from 2006 to 2013, were enrolled in this study. RESULTS: Among a total of 89 patients, 77 (86.5%) were diagnosed as having clinical TGFBI CD. Seventy-three out of 74 patients (98.6%) with granular CD type 2 (GCD2), had the p.R124H mutation. Of particular note, one patient with rapidly progressive CD had the p.R124H mutation as well as a novel nonsense variant with unknown clinical significance (p.A179*). In three patients with lattice CD type 1 (LCD1), one known mutation (p.R124C) and two novel variants (p.L569Q and p.T621P) in the TGFBI gene were identified. CONCLUSIONS: This study provides epidemiological insight into CDs in a Korean population and reaffirms that GCD2 is the most common TGFBI CD phenotype and that p.R124H is the only mutation identified in patients with GCD2. In addition, we broaden the spectrum of TGFBI mutations by identifying two novel missense variants in patients with LCD1.

Asunto(s)

Pueblo Asiatico/genética , Distrofias Hereditarias de la Córnea/genética , Factor de Crecimiento Transformador beta1/genética , Adolescente , Adulto , Anciano , Distrofias Hereditarias de la Córnea/diagnóstico , Análisis Mutacional de ADN , Femenino , Humanos , Masculino , Persona de Mediana Edad , Fenotipo , Polimorfismo de Nucleótido Simple , República de Corea , Estudios Retrospectivos , Adulto Joven

RESUMEN

This study investigates the role of impaired proliferation, altered cell cycle arrest, and defective autophagy flux of corneal fibroblasts in granular corneal dystrophy type 2 (GCD2) pathogenesis. The proliferation rates of homozygous (HO) GCD2 corneal fibroblasts at 72 h, 96 h, and 120 h were significantly lower (1.102 ± 0.027, 1.397 ± 0.039, and 1.527 ± 0.056, respectively) than those observed for the wild-type (WT) controls (1.441±0.029, 1.758 ± 0.043, and 2.003 ± 0.046, respectively). Flow cytometry indicated a decreased G1 cell cycle progression and the accumulation of cells in the S and G2/M phases in GCD2 cells. These accumulations were associated with decreased levels of Cyclin A1, B1, and E1, and increased expression of p16 and p27. p21 and p53 expression was also significantly lower in GCD2 cells compared to the WT. Interestingly, treatment with the autophagy flux inhibitor, bafilomycin A1, resulted in similarly decreased Cyclin A1, B1, D1, and p53 expression in WT fibroblasts. Furthermore, similar findings, including a decrease in Cyclin A1, B1, and D1 and an increase in p16 and p27 expression were observed in autophagy-related 7 (Atg7; known to be essential for autophagy) gene knockout cells. These data provide new insight concerning the role of autophagy in cell cycle arrest and cellular proliferation, uncovering a number of novel therapeutic possibilities for GCD2 treatment.

Asunto(s)

Puntos de Control del Ciclo Celular , Córnea/citología , Distrofias Hereditarias de la Córnea/patología , Fibroblastos/efectos de los fármacos , Regulación de la Expresión Génica , Adolescente , Adulto , Autofagia , Proliferación Celular , Niño , Distrofias Hereditarias de la Córnea/genética , Distrofias Hereditarias de la Córnea/metabolismo , Femenino , Fibroblastos/metabolismo , Citometría de Flujo , Homocigoto , Humanos , Macrólidos/química , Masculino , Persona de Mediana Edad , Adulto Joven

RESUMEN

BACKGROUND: Mutations in the transforming growth factor beta-induced gene (TGFBI) are major causes of genetic corneal dystrophies (CDs), which can be grouped into TGFBI CDs. Although a few studies have reported the clinical and genetic features of Korean patients with TGFBI CD, no data are available regarding the frequency and spectrum of TGFBI mutations in a consecutive series of Korean patients with clinically diagnosed CDs. METHODS: Patients with any type of CD, who underwent both ophthalmologic examination and TGFBI gene analysis by Sanger sequencing at a tertiary care hospital in Seoul, Korea from 2006 to 2013, were enrolled in this study. RESULTS: Among a total of 89 patients, 77 (86.5%) were diagnosed as having clinical TGFBI CD. Seventy-three out of 74 patients (98.6%) with granular CD type 2 (GCD2), had the p.R124H mutation. Of particular note, one patient with rapidly progressive CD had the p.R124H mutation as well as a novel nonsense variant with unknown clinical significance (p.A179*). In three patients with lattice CD type 1 (LCD1), one known mutation (p.R124C) and two novel variants (p.L569Q and p.T621P) in the TGFBI gene were identified. CONCLUSIONS: This study provides epidemiological insight into CDs in a Korean population and reaffirms that GCD2 is the most common TGFBI CD phenotype and that p.R124H is the only mutation identified in patients with GCD2. In addition, we broaden the spectrum of TGFBI mutations by identifying two novel missense variants in patients with LCD1.

Asunto(s)

Adolescente , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven , Pueblo Asiatico/genética , Distrofias Hereditarias de la Córnea/diagnóstico , Análisis Mutacional de ADN , Fenotipo , Polimorfismo de Nucleótido Simple , República de Corea , Estudios Retrospectivos , Factor de Crecimiento Transformador beta1/genética

RESUMEN

Granular corneal dystrophy type 2 (GCD2) is an autosomal dominant disorder that is caused by a point mutation in transforming growth factor-ß-induced gene-h3 (TGFBI), which encodes transforming growth factor-ß-induced protein (TGFBIp). Recently, we found that the autophagic clearance of mutant-TGFBIp is delayed in GCD2 corneal fibroblasts; however, any potential correlation between mutant-TGFBIp turnover and autophagy-lysosome pathway remains unknown. Here, we report that mutant-TGFBIp is accumulated and that autophagy, a key clearance pathway for mutant-TGFBIp, is induced in primary cultured GCD2 homozygous (HO) and wild-type (WT) corneal fibroblasts that express exogenously introduced mutant-TGFBIp. Mutant-TGFBI colocalized with LC3-enriched cytosolic vesicles and cathepsin D in primary cultured GCD2 corneal fibroblasts. We also observed reduced levels of raptor (regulatory-associated protein of the mammalian target of rapamycin [mTOR]) in GCD2 corneal fibroblasts and WT corneal fibroblasts expressing mutant-TGFBIp. Strikingly, treatment with MG132, a ubiquitin/proteasome system inhibitor, significantly increased the levels of both total and ubiquitinated raptor in GCD2 corneal fibroblasts. The levels of the autophagy marker LC3-II were also increased in WT corneal fibroblasts that were treated with shRNA against raptor. However, mutant-TGFBIp accumulated in autophagosomes or/and lysosomes in spite of the significant activation of basal autophagy in GCD2 corneal fibroblasts. These results suggest that an insufficient autophagy-lysosome pathway might be responsible for the intracellular accumulation of mutant-TGFBIp during the pathogenesis of GCD2.

Asunto(s)

Proteínas Adaptadoras Transductoras de Señales/metabolismo , Autofagia , Distrofias Hereditarias de la Córnea/metabolismo , Complejo de la Endopetidasa Proteasomal/metabolismo , Ubiquitina/metabolismo , Distrofias Hereditarias de la Córnea/enzimología , Humanos , Proteolisis , Proteína Reguladora Asociada a mTOR